Dzhokhar Tsarnaev, who is charged in connection with the Boston Marathon bombings, is shown in a photo from the Russian social networking site Vkontakte. / vk.com via AP

by Yamiche Alcindor, USA TODAY

by Yamiche Alcindor, USA TODAY

DARTMOUTH, Mass. -- Friends and classmates of Dzhokhar Tsarnaev can't grasp how the pot-smoking, party boy they knew is the same young man now accused of carrying out a terrorist attack.

Tsarnaev was funny, sarcastic, liked to party and frequently reeked of marijuana, said students in a sophomore residence at the University of Massachusetts-Dartmouth where the alleged bomber lived.

Several students on Tuesday described a shared shock and disbelief as classmates discovered that Tsarnaev faces federal charges of using and conspiring to use a weapon of mass destruction.

"It's like finding out your best friend is a serial killer," said Jennifer Mendez, who met Tsarnaev last year in their freshmen dorm. "He was really social and hilarious. He was one of those people who would crack one joke and make your night."

Dzhokhar Tsarnaev, 19, and his brother, Tamerlan Tsarnaev, 26, carried out two explosions that rocked the Boston Marathon on April 15, federal officials say. The bombs left three people dead and more than 260 others injured.

Last Thursday, the two allegedly gunned down Massachusetts Institute of Technology police officer Sean Collier as they were being sought by authorities. The older brother was killed in a confrontation with police early Friday morning. The younger Tsarnaev brother now faces criminal charges that carry a possible death sentence.

Mendez, 20, grew close with Dzhokar Tsarnaev. Both moved into Pine Dale Hall to start their sophomore year.

On Sunday, the FBI searched Tsarnaev's dorm room in that building and seized BBs, a large pyrotechnic, and "a black jacket and a white hat of the same general appearance as those worn by Bomber Two at the Boston marathon on April 15," according to the criminal complaint filed against Tsarnaev.

Mendez can't imagine the motives behind Tsarnaev's alleged actions. Like many in Pine Dale Hall, she didn't connect the blurry picture of Suspect Two to their classmate.

In the years she knew him, Mendez said Tsarnaev just enjoyed playing soccer, talked about his years wrestling and mulled over the demands of college life: professors, classes, and homework. Partying and drinking filled their days, she said, and Tsarnaev did not show signs he was becoming radical or changing in any way.

Her best memories are of the two sitting outside Maple Ridge Hall, the freshman dorm they shared, talking about school and the excitement of being in college.

Mendez, a biology and chemistry double major, last partied with Tsarnaev last semester. The demands of her studies slowed her partying down this semester, but Tsarnaev seemed normal when she sat in politics class with him or when she passed him on the way to his third-floor dorm.

Tsarnaev shared that third-floor dorm room with another student, said Patrick Yaghoobian, 20, who lived next -door to the pair all school year.

"He smoked a lot of pot," he said of Tsarnaev on Tuesday afternoon. "He smelled like it every day."

A strong smell of marijuana emanated from the room throughout the school year while Tsarnaev, himself, reeked of the drug, Yaghoobian said. The smell was absent last Monday when the bombing took place.

He said Tsarnaev was a quiet kid who walked around with the same blank, emotionless expression seen in many of the photos released by the FBI.

The Millbury, Mass., native added that there were no signs of radicalism: "I've looked into his room a few times, and there was nothing religious or nothing that screamed out he was Muslim."